[john walker's workshop]

batteries are generally good for their stated life expectancy. 60, 72 months. after a long slow charge, test the gravity of the fluid with a hydrometer. the cell readings should be in the middle of the good range. if you find one or more cells in the fair, or poor range, or cells that peg the needle at the top (sulphated), the battery is probably over, regardless of it's proposed lifespan. the next test, after it's fully charged, would be a load test, but you would have to take it to a shop. 150A for 15 seconds, and watch the gauge for how low the voltage goes. it should hold at least 10.5 V during the test. if it drops to 5 or 6, it's tits. lots of batteries sit in warehouses for a long time, decomposing, before they're shipped to schucks.